During production of a display panel, the TFT plays an important role on an array substrate. The TFT generally comprises a gate which is arranged on a base plate, an active layer which is arranged on the gate and is insulated from the gate, and a source and a drain which are arranged oppositely and electrically connected with the active layer, respectively. When a current is applied to the gate through a circuit on the base plate, the current which is applied to the source is transported to the drain through the active layer, and pixel units of the display device are drove to display an image. Currently the TFT has a poor reliability, so that the electrical performance of TFT is not stable.